Cellulose derivative compositions



Patented June 30, 1936 PATENT- OFFICE CELLULOSE DERIVATIVE COMPOSITIONSJames K. Hunt and George H. Latham, Wilmington, Del., assignors to E. I.du Pont de Nemours & Company, Wilmington, DeL, a corporation of DelawareNo Drawing.s

Claims.

This invention relates to cellulose derivative compositions containingnon-drying and semidrying fatty bodies and agents for inhibitingrancidity development thereof and, more particu- 5 larly, to cellulosenitrate compositions employed in the manufacture of artificial leather,and the like.

Numerous compounds have heretofore been suggested as agents forinhibiting rancidity in non-drying and semi-drying fatty bodies and afew compounds have been suggested as rancidity inhibiting agents for usein cellulose derivative compositions. However, the heretofore suggestedcompounds are usually either unsatisfactory as regards the inhibition ofrancidity, or they seriously affect the initial color of cellulosederivative dopes, cause discoloration of films deposited from the dopeson exposure to the sunlight, render such films sensitive to water.

cause spotting or fading of the color, or else have an objectionableodor. Most of the prior art has related only broadly to the inhibitionof rancidity in oils and has given no indication of the suitability ofsuggested compounds for use in cellulose derivative dopes. The mere sugestion of a compound as a rancidity inhibitor for oils is ofpractically no value toward the selection of an agent having that uniquecombination of properties which will make it satisfactory for use incellulose derivative dopes, particularly white or light coloredcellulose nitrate compositions.

An object of the present invention is to provide improved cellulosederivative compositions for coating artificial leather, and the like,containing a non-drying or semi-drying fatty body and a rancidityinhibiting agent therefor. A further object is to provide suchcompositions containing a non-drying or semi-drying fatty body having atendency to become rancid and having, in the raw state, a normal iodinenumber below 135 and a rancidity inhibiting agent there- '"for whichwill not affect the initial color of the composition, Causediscolorationof films de- Application July 15, 1933, erial No. 680,656

posited therefrom on exposure to the sunlight, render said filmssensitive to water, cause spotting or fading of the color, or have anobjectionable odor. Other objects of the invention will be apparent fromthe description given herein- 5 after.

The above objects are accomplished according to the present invention byincorporating in a cellulose derivative coating composition containing anon-drying or semi-drying fatty body havl0 ing a tendency to becomerancid and having, in the raw state, a normal iodine number below 135,but preferably below 120, an agent selected from the group consisting of(1) aryl boric acids, and (2) phenols having two aromatic nuclei sep- 5arated, in one of the positions directed by phenolic hydroxyl, by anatom chosen from the group consisting of oxygen, secondary carbon'andtertiary carbon.

Among the aryl boric acids found particularly 20 adapted for the purposeof the present invention are ljIKOH): B(0H)i a gfla p-tolyl boric acid30 phonyl boric acid These compounds are expressed comprehensively bythe formula R-B-Rl, where R is any monovalent organic radical joined tothe boron atom through an aromatic carbon atom, and R1 is 35 hydroxyl'or a monovalent organic radical joined to boron through an aromaticcarbon atom. Other suitable boric acids of this general formula arenaphthyl boric acid, di-p-anisyl boric acid, di-p-naphthyl boric acid,and p-carboxy- 4o phenyl boric acid.

Phenols having two aromatic nuclei separated, in one of the positionsdirected by phenolic hydroxyl, by an atom chosen from the groupconsisting of oxygen, secondary carbon, and tertiary 45 carbon foundparticularly useful in the present invention include:-

OH OH OH mo- -on. n- -cn. mc- -om H H H Dihydroxydiphenyl Dihydro diphenl Dihydroxydl-o-tolyl dimethylmethane methyl ri thane y dimethyl methane(diphenylolpropane) o-Hydroxy di- 0 H:

phenyl ether pHydroxy diphenyl ether CHaOH Unit of diphenylolpropaneiormaldehydc condensation product, from which polymers aredoubtless formed.

OH H H H10 CHa Phenol-dipentcne unit from which lymers are doubtlessformed.

he 1 and cresol condensate with dipentcne are similarly formed. Thisclass of phenols is expressed comprehensively by the formula RX-R',where X is oxygen, secondary carbon, or tertiary carbon; R is an orthoor para-hydroxy aryl radical; and R is an organic radical having atleast one aromatic nucleus. R, for example, may be 2-hydroxyphenyl,4-hydroxyphenyl, 4-hydroxy-8-methylphenyl, 4-hydroxy-3-chlorophenyl,4-hydroxya-naphthyl, 4-hydroxy 3-methyl-5-chlorophenyl,4-hydroxy-3,5-dimethylphenyl, et cetera. R, for example, may be the sameas R or may be phenyl, o-tolyl, p-tolyl, xylyl, p-chlorophenyl,4-methyl- 4-(p-hydroxyphenyl) cyclohexyl, et cetera. The essential unitis the linkage X which, if carbon, must carry not more than one hydrogenatom. x, if carbon, may have attached thereto one or two alkyl or arylradicals such as methyl, ethyl butyl, i-butyl, heptyl, cyclohexyl,phenyl, naphthyl, et cetera. Phenols of the type R-X-R' are especiallyvaluable because non-drying or semi-drying fatty bodies containing themare not only stable toward rancidity development, but are highlyresistant to discoloration. It is believed that the latter property inparticular is due to the stability of the phenol toward oxidativechanges, and this, in turn, is due to the linkage x in the generalformula for the phenol.

It is believed that these oxidative changes are due to a quinoid-likedegradation of the phenol, and this cannot occur if the phenolichydroxyl is blocked" in one of the ring positions which it directs (viz.ortho or para, and especially para) 5 by a structure of the type X.

It has been found that the above classes of compounds have propertieswhich are remarkably well adapted for using said compounds in cellulosederivative composition containing nondrying and semi-drying oils andother fatty bodies tending to become rancid. That is, these compoundsare eflective for inhibiting rancidity in compositions containingnon-drying and semi-drying fatty glycerides which have a tendency tobecome rancid and have, in the raw state, a normal iodine number below135 and particularlyin such oils having an iodine number below 120; donot give an objectionable odor to the compositions, do not give rise toobjectionable discoloration of the compositions, and do not render thecompositions sensitive to water.

Although both of the above classes of compounds have been foundeffective for this purpose, the aryl boric acids and the phenols havingtwo aromatic nuclei separated, in one of the positions directed byphenolic hydroxyl, by a tertiary carbon, have been found particularlyeiiective.

The phenols having two aromatic nuclei separated, in the para positiondirected by phenolic hydroxyl. by a secondary carbon atom or a tertiarycarbon atom, more particularly a tertiary carbon atom, are especiallyeffective in white and light colored cellulose derivative compositionsbecause of their exceptionally great resistance to discoloration,presumably due to the stability of these compounds toward oxidationchanges.

In order to test the effect of our compounds in coating compositions ordopes employed in the manufacture of artificial leather a representativedope was prepared as follows:

Inhibitor 0.36 (2% based on castor oil content) The cellulose nitratewas dispersed in a mixture of the ethyl alcohol and ethyl acetate, andthe pigment ground in a portion of the castor oil. -The remaining castoroil was mixed with the cellulose nitrate dispersion, following which thepigment in oil was added and the whole thoroughly mixed. The inhibitorwas added as an alcoholic solution along with the pigment in oil.

In order to determine the effect of the inhibitors on the color of adope of this type, the pigment consisted of lithopone or a mixture of98.5% lithopone and 1.5% ultramarine blue. The compositions containingthese pigments, because of their white or pale blue color, are highlysusceptible to discoloration by inhibitors of the wrong type, and alsolend themselves well to observations for water spotting".

By the term water spotting is meant a color change, such as fading,which takes place when the artificial leather is brought into contactwith water.

A suitable procedure for testing ran'cidity inhibitors in compositionsof the above type fol- 76 lows: Various dopes are applied to pieces of,fabric in the usual manner for making artificial leather, which treatedpieces of fabric are then subjected to the following tests. A sample oftreated fabric of standard size (e. g., 2" x 5") is placed in a smallglass-stoppered flask and stored at a temperature of about 65 C. Thevarious bottles are opened daily, or at other suitable intervals, and,from the odor emitted, a determination as to when rancidity develops ismade.

The various pieces of treated fabric are subjected to exposure to thelight from a glass-enclosed carbon are for 16 hours and the change incolor is compared with that of a sample of cloth treated with the samedope containing no inhibitor, in order to determine the effect of theinhibitors on the color change caused by exposure to sunlight.

A small strip of each sample of the treated fabric is immersed in waterfor. 2 days and then dried. A comparison of the samples will disclosethe effect of the inhibitors on water spotting or color change caused bythe water.

The following tablediscloses the results obtained by the use of certainof our preferred inhibitors when incorporated in an artificial leatherprepared as above described. In each case, 2% of the inhibitor, based onthe castor oil, was employed:

Table I iidfi C l W ranc y c or ater ln'mbtor fdevelopchanges spottingment None 7 None None O-hydroxydxphenyl ether 100+ Slight NonePhenoldipentene condensation piu 100+ None None Cresol-dxpentenecondensation pro not 100+ None None Guaiaool-dipentene condensationproduct 100+ Slight None Dihydroxydiphenyldimethyl In ane 100+ None NoneDihydroxydi o tolyl dimetbyl methane 100+ None NoneDihydroxydlphenylmethylmethane 100+ Slight NoneDiphenylolpropane-iormaldehyde complex 100+ None None Phenyl boric acid100+ None None P-tolyl boric acid 100+ None None The sign indicates norancidity after number of days shown.

None of these compounds had any efiect on the initial color of theartificial leather or gave the artificial leather an objectionable odor.In.

inhibitor may be used to advantage. The proportion of inhibitor willdepend upon the particular type of composition, and especially the kindof oil used. It is practically never necessary to use more than 5% of.inhibitor, based on the oil, and in some cases as little as 0.25% isuseful. The

percent of inhibitor is given by weight and not by volume.

The inhibitors have been disclosed specifically in coating compositionsfor dopes such as are generally used in the manufacture of artificialleather, said coating compositions containing castor oil. However, theinhibitors are adapted to be employed in other types of cellulosederivative compositions containing non-drying and semi-drying fattybodies which have a tendency to become rancid and have, in the rawstate, a normal iodine number below 135, or in such products whenemployed for other purposes. For example, the inhibitors of the presentinvention may be employed in cellulose derivative compositionscontaining resins and softeners derived from the various fatty acidglycerides.

Among the non-drying and semi-drying oils which may be treatedsatisfactorily with the inhibitors of the present invention, are oliveoil, rapeseed oil, codliver oil, corn oil, peanut oil, cocoanut oil,cottonseed oil, palm oil, lard oil,

neatsfoot oil, butter fat, lard, beef tallow, wool jected to varioustreatments, such as blowing -with air at elevated temperatures, simpleheat treatments, and the like, or the oils may be employed in makingresins and softeners for use in artificial leather and similarcompositions. Accordingly, the expression non-drying and semi-dryingbodies having a tendency to become rancid and having, in the raw state,a normal iodine number below 135", as used in the claims, is intended toinclude bodies of a resinous, oily, or waxy nature, having an iodinenumber below 135, which tend to become rancid with exposure to theatmosphere. Glycerol esters are most liable to rancidification; hencethis invention is most concerned with such esters. However, the presentinhibitors can also be added with advantage to other fatty acid esters,such as those of ethyl alcohol, butyl alcohol, mixtures of higheraliphatic monohydric alcohols, ethoxyethyl alcohol, ethylene glycol,propylene glycol, diethylene glycol, pentaerythritol, benzyl alcohol, etcetera. Fatty glycerides to which the present inhibitors can be addedwith especial advantage are those given in International Critical TablesVolume 11, pages 201205, under General Index numbers 0.5-51 and 95-149inclusive. The terminology used in the claims, referred to above, isintended to include all the above monohydric or polyhydric alcoholesters.

While certain compounds of general classes and certain fatty bodiesemployed in particular compositions have been disclosed, it is to beunderstood that other compounds of the same class may be employed fortreating other fatty bodies of the type described, and the proportionsand the constituents of the compositions in which they are employed maybe widely varied without departing from the spirit of the invention.Accordingly, the scope of the invention is to be limited solely by theappended claims construed as broadly as permissible in view of the priorart.

We claim:

1. A composition comprising a cellulose derivative, a, fatty substanceof the group consisting of non-drying and semi-drying bodies having atendency to-become rancid and having, in the raw state, a normal iodinenumber below 135, and, as a rancidity inhibitor therefor, aphenol-dipentene condensation product in a small percent based on thefatty substance.

- of the'group consisting of: non-drying and semistance.- a

3. A composition comprising a Iattysubstance' drying bodies having atendency to become ranold and having in the raw state, a normal iodinenumber belowl35, and, as a rancidity inhibitor therefor, a phenoldipentenecondensation prodnot in a small percentbased on the fattysubhaving a: tendency to become rancid and, as a rancidity inhibitortherefor, a phenol-dipentene condensation product in a small percentbased on the fatty substance.

4. A composition, comprising an organic compound normally tending todeteriorate on storage and, as a deterioration inhibitor therefor, aphe- -nol-dipentene condensation product in a. small percentbasedonsaid'organiccompound; I

5. A composition comprising a cellulose deriva tive, a fatty substanceor the group consisting o! non-drying and'semi-dr'yini: bodieshaving a Itendency to become. rancid and having, in the raw state, a normal iodinenumber below 135, and, as

arancidity inhibitor therefor, a condensation product ofphenol anddipentene in a small per- 7 cent based onthe fatty substance.

GEORGE H. LATHAM.

